1. Field of the Invention
This invention relates generally to pressurized containers, and more particularly, to a gas storage and delivery system for restoring and maintaining pressure as it is depleted from pressurized containers such as aerosol dispensers, bottles of carbonated beverage, fire extinguishers using water or foam, and the like.
2. Prior Art
Pressurized containers are commonly used to dispense many products, including paint, lubricants, cleaning products, hair spray, and food items. These containers are typically aerosol dispensers in which the product is stored under pressure with a suitable propellant. Dispensing of the product occurs when a discharge nozzle is depressed, permitting the pressurized product to be forced out through the nozzle, usually as a spray, stream or foam. As product is depleted from the container, the pressure exerted by the propellant decreases, especially evident with compressed gases, and may become diminished to the extent that all of the product cannot be dispensed from the container, or desired characteristics are not achieved.
Many products, e.g., hair spray, require a carrier in addition to the propellant component, e.g., alcohol, that dries quickly upon discharge from the container. Volatile organic compounds (VOCs) such as propane, isobutane, dimethyl ether, and the like, are suitable as propellants for many products, but their use is limited due to environmental concerns. For instance, under some current regulations no more than 55% of the contents of the container can comprise a VOC. In an aerosol dispenser, as much as 25% of the VOC could be required for use as a propellant, leaving about 30% VOC in the product. This 25% reduction typically is made up with water, which does not dry as quickly as the VOC, resulting in a “wet” product when used.
Carbon dioxide (CO2) is environmentally friendly, and is therefore useful as an aerosol propellant, but its use has been limited due to the drop off in pressure from start to finish as the product is used. For example, in a typical situation the starting pressure might be 100 psig and the finishing pressure only 30 psig. At this low finishing pressure all of the product may not be discharged, and/or proper aerosolization may not be obtained.
Carbonated beverages are also bottled under pressure, usually by a pressurized inert gas, such as CO2, placed in the bottle along with the beverage. Over time, the pressure of the gas may decrease, resulting in a “flat” drink. This is particularly true when plastic containers are used to bottle carbonated beverages. The shelf life of such products may be undesirably short.
Further, cans of pressurized gas are provided for cleaning dust and the like from sensitive equipment, such as computers, computer keyboards, etc., by blowing a pressurized stream of propellant onto the equipment. Currently available products for this purpose use a VOC (e.g., Dymel® by DuPont) as the propellant. These materials are relatively expensive for the intended use.
Accordingly, there is a need for a system to replenish and maintain a desired pressure in pressurized containers, such as aerosol dispensers and carbonated beverages, and particularly to such a system that is inexpensive and environmentally friendly.